# Feature Reduction

Originally published: 2019-09-02
Canonical URL: /2019/Sep/feature-reduction/

_(looking at baby/toddler photos a year apart)_ "How does he look so different and yet so the same at the same time?"

"Just in case that was non-rhetorical, the answer is that your brain evolved to be good at factorizing overall appearance into orthogonal 'personal appearance' and 'age appearance' dimensions that can be tracked separately, just as [_x_, _y_] = [1, 2] and [4, 2] are so different with respect to _x_, and yet so the same with respect to _y_, at the same time."